Spontaneous urinary extravasation: detection rate with 64-row multidetector computed tomography in patients presenting with acute abdomen.

The aim of this study was to detect the rate of spontaneous urinary extravasation (SUE) with computed tomography (CT) in patients presenting with acute abdomen. Seven hundred thirteen abdominal CT examinations with i.v. contrast media requested mainly from the emergency department and urology clinics for sudden onset abdominal pain, flank pain, nonspecific abdominal pain with nausea and vomiting, and renal colic between September 2007 and August 2011 were retrospectively reviewed. Only adult patients were included in the study. Three patients with SUE were detected. One had a mid-ureteral stone while the etiology for the other two patients was unknown. Two of the patients were treated conservatively; one was treated with stenting with a double-j catheter. SUE should be considered in the differential diagnosis of patients presenting with acute abdomen and perinephric-periureteral fluid collection inconsistent with stone size and who are occasionally stone free. Early and precise diagnosis of SUE plays an important role in the management protocol of patients presenting with acute abdomen.

Diffusion-weighted MR imaging of kidneys in renal artery stenosis.

OBJECTIVE: The purpose of our study was to evaluate perfusion and diffusion of kidneys in renal artery stenosis (RAS) and any correlation between stenosis and ADC values and whether this imaging modality may be a noninvasive complementary assessment technique to MR angiography before interventional procedures. MATERIALS AND METHODS: Twenty consecutive patients suspected of having renal artery stenosis were evaluated with renal MR angiography to exclude stenosis and were then included in the study. Transverse DW multisection echo-planar MR imaging was performed. In the transverse ADC map, rectangular regions of interest were placed in the cortex on 3 parts (upper, middle, and lower poles) in each kidney. ADCs of the kidneys were calculated separately for the low, average, and high b-values to enable differentiation of the relative influence of the perfusion fraction and true diffusion. The ADC values of 39 kidneys (13 with renal artery stenosis and 26 normal renal arteries) were compared, and the relationship between stenosis degree and ADC values was calculated. RESULTS: RAS was detected in 11 of 20 (55%) patients with MRA. Thirteen of 39 kidneys demonstrated RAS, and 26 were normal. The ADClow (1.9+/-0.2 versus 2.1+/-0.2; P=.020), ADCaverage (1.7+/-0.2 versus 1.9+/-0.1; P=.006), and ADChigh (1.8+/-0.2 versus 2.0+/-0.1; P=.012) values were significantly lower in patients with kidneys with arterial stenosis than that in patients with kidneys with normal arteries. Statistical analysis revealed that stenosis degree correlated strongly with ADClow (r=-.819; P=.001), ADCaverage (r=-.754; P=.003), and ADChigh (r=-.788; P=.001). The ADClow, ADCaverage, and ADChigh values were significantly lower in patients with kidneys with arterial stenosis than that in patients with kidneys with normal arteries. CONCLUSION: We think that DW MR imaging of kidneys with RAS can help determine the functional status of a renal artery stenosis.

Alvarado scores and pain onset in relation to multislice CT findings in acute appendicitis.

PURPOSE: To determine the correlation between clinical and multislice computed tomography (MSCT) findings of early- and late-stage acute appendicitis. MATERIALS AND METHODS: The study was conducted between June 2003 and February 2006 with 143 patients. Patients were divided into 3 groups according to Alvarado scores: group 1 (n = 18; 13%; score: 1-4), group 2 (n = 70; 49%; score: 5-7), and group 3 (n = 55; 38%; score: 8-10). Abdominal MSCT results were compared to histopathological diagnoses. Patients were then divided into 2 other groups according to pain onset (MSCT performed within the first 12 h of pain onset and MSCT performed thereafter). RESULTS: Histopathological findings were normal in 13 of the 143 patients (9%). The positive predictive value of MSCT did not significantly differ between the 3 Alvarado groups (92.8% in group 1, 95.1% in group 2, and 98.0% in group 3). Additionally, the positive predictive value of MSCT did not differ whether the scans were performed within the first 12 h of pain onset or thereafter (88% and 89%, respectively; P = 0.89). CONCLUSION: MSCT should be performed even in patients in whom the clinical suspicion of appendicitis is low. MSCT is effective in patients with early-stage appendicitis.

Posterior reversible encephalopathy syndrome: incidence of atypical regions of involvement and imaging findings.

OBJECTIVE: Posterior reversible encephalopathy syndrome (PRES) is classically characterized as symmetric parietooccipital edema but may occur in other distributions with varying imaging appearances. This study determines the incidence of atypical and typical regions of involvement and unusual imaging manifestations. MATERIALS AND METHODS: Seventy-six patients were eventually included as having confirmed PRES from 111 initially suspected cases, per imaging and clinical follow-up. Two neuroradiologists retrospectively reviewed each MR image. Standard sequences were unenhanced FLAIR and T1- and T2-weighted images in all patients, with diffusion-weighted imaging (n = 75) and contrast-enhanced T1-weighted imaging (n = 69) in most. The regions involved were recorded on the basis of FLAIR findings, and the presence of atypical imaging findings (contrast enhancement, restricted diffusion, hemorrhage) was correlated with the severity (extent) of hyperintensity or mass effect on FLAIR. RESULTS: The incidence of regions of involvement was parietooccipital, 98.7%; posterior frontal, 78.9%; temporal, 68.4%; thalamus, 30.3%; cerebellum, 34.2%; brainstem, 18.4%; and basal ganglia, 11.8%. The incidence of less common manifestations was enhancement, 37.7%; restricted diffusion, 17.3%; hemorrhage, 17.1%; and a newly described unilateral variant, 2.6%. Poor correlation was found between edema severity and enhancement (r = 0.072), restricted diffusion (r = 0.271), hemorrhage (r = 0.267), blood pressure (systolic, r = 0.13; diastolic, r = 0.02). Potentially new PRES causes included contrast-related anaphylaxis and alcohol withdrawal. CONCLUSION: This large series of PRES cases shows that atypical distributions and imaging manifestations of PRES have a higher incidence than commonly perceived, and atypical manifestations do not correlate well with the edema severity.

Proton MR spectroscopy in the diagnosis of early-stage subacute sclerosing panencephalitis.

Subacute sclerosing panencephalitis (SSPE) is a progressive, fatal neurological disorder of childhood and early adolescence. In this report, we present brain magnetic resonance spectroscopy (MRS) and conventional magnetic resonance MR imaging findings of early-stage (stage II) SSPE in an 8-year-old child. MRS demonstrated increased myo-inositol/creatine and choline/creatine ratios, and a decreased N-acetyl aspartate/creatine ratio. Conventional MR imaging demonstrated nonspecific, patchy T2 hyperintensities in the periventricular white matter and a nonspecific focus of T2 hyperintensity in the right frontal subcortical white matter. The MRS findings suggested active inflammation and demyelination as is seen in early-stage SSPE.

Transalar encephalocele associated with Wegener granulomatosis and meningeal enhancement: case report.

Transalar encephaloceles are rare lesions that do not fit the standard classification of basal encephaloceles. Typically, these lesions present in adulthood, with nonspecific symptoms. We report here a case of a patient with Wegener disease in whom a large transalar encephalocele posterior to the sinus was noted when he was preoperative for left maxillary sinus surgery. The encephalocele demonstrated irregular peripheral enhancement along the margin--a very uncommon finding--as well as contrast enhancement of the basal meninges, which can be seen occasionally with Wegener granulomatosis.

Multi-slice CT angiography of small cerebral aneurysms: is the direction of aneurysm important in diagnosis?

PURPOSE: Multi-slice CT (MSCT) has great potential in evaluation of vascular structures. Our purpose was to investigate if there is any difference in detection of superiorly, inferiorly and horizontally directed small cerebral aneurysms (<5 mm) on MSCTA compared to digital subtraction angiography (DSA) or surgery. MATERIALS AND METHODS: One hundred and three consecutive patients who underwent MSCTA and DSA or surgery were included in the study. MSCTA and DSA results were evaluated independently by two different neuroradiologists who performed aneurysm detection, quantitation, and characterization using 2D multiplanar reconstructions, 3D maximum intensity projection and volume-rendered techniques. FINDINGS: MSCTA detected 49 small cerebral aneurysms (<5 mm) in 37 (36%) of 103 patients. The overall sensitivity, specificity, and accuracy of MSCTA for detecting small aneurysms were 0.85, 0.65, and 0.79, respectively. There was moderate agreement between MSCTA and DSA/surgery for detecting small aneurysms (kappa: 0.51). The sensitivity of detecting small aneurysms directed superiorly, inferiorly and horizontally was 0.94, 0.84, and 0.75, respectively. There was no statistically significant difference in detection between small aneurysms directed superiorly, inferiorly and horizontally on MSCTA (P > 0.05). CONCLUSION: The direction of small cerebral aneurysms is not important in diagnosis on multi-slice CT scanners, although the detection of small cerebral aneurysms with superior or inferior direction is slightly easier than the detection of horizontally directed aneurysms.

CT perfusion imaging in the early diagnosis of acute stroke.

Early diagnosis of acute cerebral infarction is critical due to the time limit of thrombolytic treatment. Cerebral computed tomography (CT) perfusion imaging is a new technique, which appears to provide early diagnosis of major vessel occlusions in the brain. CT perfusion imaging also provides valuable information about the hemodynamic status of ischemic brain tissue. In this report, we present the CT perfusion findings in comparison to the non-contrast CT and diffusion-weighted (DW) magnetic resonance (MR) imaging findings in two cases of acute cerebral infarction. Non-contrast CT findings were non-specific in the first case and there was minimal hypoattenuation in the superior aspect of the lentiform nucleus in the second case. CT perfusion imaging demonstrated significant perfusion defects in the middle cerebral artery territory in both cases. DW-MR imaging confirmed acute infarctions, which were smaller than the perfusion defect areas in the CT perfusion imaging in both cases.

MR imaging and ultrasound of fetal cervical cystic lymphangioma: utility in antepartum treatment planning.

We present a case of fetal cystic lymphangioma that was initially diagnosed by ultrasonography and further evaluated by prenatal MR imaging. MR imaging findings aided in improved delineation of the neck mass. T2-weighted MR images revealed partial compression of the airway by the neck mass. This information was useful in the decision to use ex utero intrapartum treatment (EXIT) and helped surgeons in planning their approach to establish airway control during delivery.

Anatomy and frequency of large pontomesencephalic veins on 3D CT angiograms of the circle of Willis.

BACKGROUND AND PURPOSE: The pontomesencephalic veins (PMVs), especially the anterior PMV, are sometimes large enough that they could potentially affect the interpretation of CT angiograms of the circle of Willis. We investigated the frequency and anatomy of visible PMVs on 3D CT angiograms. METHODS: CT angiograms of 211 consecutive patients who underwent CT angiography for a variety of clinical indications were evaluated retrospectively. Images evaluated by consensus between two neuroradiologists were maximum intensity projection and volume-rendered 3D CT angaiograms. RESULTS: Visible PMVs were present on 3D CT angiograms in 11 (5.2%) of 211 patients. Eight of 11 patients had a visible anterior PMV behind the basilar artery. In four patients, the venous caliber of the anterior PMV was sufficiently large enough to be potentially confused with arterial structures. In one patient, 3D CT angiography revealed a large anterior PMV (approximately 2.6 mm in diameter) in the interpeduncular cistern, which had been mistaken for subarachnoid hemorrhage on a nonenhanced CT scan. Two patients had interpeduncular veins of the anterior PMV draping over the dome of a basilar tip aneurysm. In only one patient was the anterior PMV visible possibly owing to arteriovenous malformation. One patient had visible lateral mesencephalic veins, and four patients had visible transverse pontine veins. In one case, on certain views, the transverse pontine veins appeared to arise from the basilar artery. CONCLUSION: Because of their small size, PMVs were seen only infrequently on 3D CT angiograms, but neuroradiologists should be familiar with the normal variants of large PMVs to avoid diagnostic and anatomic confusion.

Multi-section CT angiography for detection of cerebral aneurysms.

BACKGROUND AND PURPOSE: Multi-section CT has great potential for use in vascular studies. Our purpose was to determine the accuracy of multi-section CT angiography in detecting cerebral aneurysms compared with digital subtraction angiography or surgery. METHODS: One hundred consecutive patients who underwent multi-section CT angiography and either digital subtraction angiography or surgery were included in the study. Multi-section CT angiography and digital subtraction angiography results were evaluated independently by different neuroradiologists who performed aneurysm detection, quantitation, and characterization by using 2D multiplanar reconstructions, 3D maximum intensity projection, and volume-rendered techniques. RESULTS: When using intra-arterial digital subtraction angiography or surgery, 113 aneurysms (true positives and false negatives) were detected in 83 of the 100 patients. A total of 106 aneurysms (true positives) were confirmed by using digital subtraction angiography or surgery, or both. Seven aneurysms were missed when using multi-section CT angiography. Eight aneurysms were not confirmed by digital subtraction angiography and were considered to be false positive evaluations. The sensitivity for detecting aneurysms < 4 mm, 4 to 10 mm, and > 10 mm on a per-aneurysm basis was 0.84 (95% confidence interval: 0.72, 0.92), 0.97 (95% confidence interval: 0.91, 0.99), and 1.00 (95% confidence interval: 0.88, 1.00), respectively. The sensitivity, specificity, and accuracy of multi-section CT angiography for detecting aneurysms on a per-patient basis were 0.99 (95% confidence interval: 0.96, 1.00), 0.88 (95% confidence interval: 0.69, 0.94), and 0.98 (95% confidence interval: 0.95, 1.00), respectively. CONCLUSION: Multi-section CT angiography has a high sensitivity in detecting aneurysms (especially aneurysms > 3 mm). However, CT angiography is currently not sensitive enough to replace digital subtraction angiography.

Diffusion-weighted imaging in the setting of diffuse cortical laminar necrosis and hypoxic-ischemic encephalopathy.

BACKGROUND AND PURPOSE: As is the case for CT scans, MR images may occasionally appear deceptively normal unless proper windowing is used. We sought to illustrate the necessity for proper windowing and for assessing the gray-white matter differentiation on diffusion-weighted (DW) images in the setting of hypoxic-ischemic encephalopathy. METHODS: Six comatose patients (age range, 34-56 years) underwent MR imaging in the early phase (range, 1-5 days) after severe anoxic insult. T2-weighted, turbo fluid-attenuated inversion-recovery, and DW images were obtained in all six patients, with contrast-enhanced T1-weighted images obtained in four and apparent diffusion coefficient (ADC) maps in five of the six patients. RESULTS: At presentation, each of the six patients had symmetric, uniform hyperintensity in the cortex (mean ADC, 0.35 x 10(-3) mm(2)/s) relative to the white matter (mean ADC, 0.91 x 10(-3) mm(2)/s) on DW images. Each also had a poor outcome: brain death in four patients and a permanent vegetative state in two patients. CONCLUSION: The appearance of the MR images in the setting of diffuse cortical laminar necrosis can be deceptive to the unwary radiologist. The key to correct interpretation is proper windowing and the marked gray-white matter differentiation on spin-echo images but best seen on properly windowed DW images in the early subacute phase. This appearance also implies an extremely poor outcome, either a permanent vegetative state or brain death.

Multi-slice CT angiography in evaluation of extracranial-intracranial bypass.

Multi-slice CT (MSCT) scanners provided significant improvement in vascular applications. In this study, our purpose was to determine the clinical utility of MSCTA in evaluation of extracranial-intracranial (EC-IC) bypass patency. Eleven (4 men and 7 women; mean age, 46 years; age range, 19-68 years) consecutive patients who underwent MSCTA and DSA after EC-IC bypass surgery were evaluated retrospectively. All patients underwent DSA within 3 weeks of MSCTA. The indications for EC-IC bypass were severe stenosis or occlusion of intracranial arteries in seven patients and therapeutic occlusion of intracranial artery for unclippable giant aneurysm in four patients. Ten patients underwent superficial temporal artery (STA)-middle cerebral artery (MCA) bypass and one patient underwent occipital artery-posterior cerebral artery (PCA) bypass. Eight STA-MCA bypasses in six patients were patent on MSCTA which were confirmed on DSA. Two STA-MCA bypasses and one occipital artery-posterior cerebral artery (PCA) bypass were occluded in three patients on MSCTA and DSA. In one patient, minimal stenosis of the STA-MCA bypass was identified on MSCTA and DSA. In 1 patient, STA-MCA bypass was not well seen on MSCTA and suspected for occlusion. DSA identified the occlusion of bypass on this patient. MSCTA seems to be a very promising noninvasive technique in evaluation of EC-IC bypass.

Neuroimaging in metabolic disorders.

Although genetic and chemical studies are most helpful for the diagnosis of metabolic disorders of the brain, there is a role for neuroimaging to quantify the degree of brain involvement and the response to therapy. Also, in some instances the imaging pattern can guide in the selection of genes or gene products to be studied.

Interatrial shunt: diagnosis of patent foramen ovale and atrial septal defect with 64-row coronary computed tomography angiography.

PURPOSE: The aim of this study was to investigate the frequency with which interatrial shunts are found during routine coronary computed tomography (CT) angiography and to describe imaging characterizations of patent foramen ovale (PFO), atrial septal defect (ASD), and atrial septal aneurysm (ASA). MATERIALS AND METHODS: A total of 1081 adult patients were evaluated retrospectively for interatrial shunting; 77 were excluded from the study. CT diagnosis of PFO was defined as (1) a channel-like appearance of the interatrial septum (IAS) and (2) a contrast agent jet flow from the left atrium (LA) to the right atrium (RA). ASD was defined as (1) the IAS resembling a membrane with a hole and (2) a contrast jet flow between the two atria. ASA was identified by detecting a minimum 10-mm protrusion of the LA beyond the IAS into the RA. RESULTS: Among 1004 patients, 86 patients (8.6%) were diagnosed to have PFO. Another 23 patients (2.3%) had a hole in the IAS and were diagnosed as having ASD: 21 with an ostium secundum-type ASD and 2 with the sinus venosus type. ASA accompanied ASD in three patients. CONCLUSION: Electrocardiography-gated CT using the saline-chaser contrast injection technique that is routinely used for coronary arterial imaging can be used to detect interatrial shunts. The technique can also serve as a method for differentiating PFO, ASD, and ASA.

Inborn errors of metabolism presenting in childhood.

Neurodegenerative and neurometabolic disorders may cause significant morbidity and mortality in children. Imaging is important in early diagnosis of metabolic disorders and in determining the extent of brain injury. Especially after the development of new techniques such as diffusion-weighted magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS), neuroimaging plays more important role in the diagnosis and management of these disorders. In these disorders, usually a mutation causes a clinically significant block in one or more metabolic pathways. This blockage usually results in either a deficiency of the product or in an accumulation of substrate with damage induced by either storage or toxicity. The presenting symptoms are usually nonspecific. In some of the metabolic disorders, long-term dietary or medical treatment options are available, and to make an early diagnosis in these disorders is important before the brain damage occurs. Prompt diagnosis, particularly in treatable disorders, is crucial to prevent neurological sequelae or death. If treatment is indeed available, neuroimaging also provides a baseline in evaluation of the efficacy of treatment. Therefore, the neuroradiologist should be aware of these disorders to prevent devastating results of delayed diagnosis. Metabolic disorders affecting the central nervous system, both gray and white matter can be classified by involvement of the primary cellular organelle as lysosomal, peroxisomal, mitochondrial disorders, or biochemical classification can be made as amino acid and organic acid metabolism defects or primary white matter disorders. This article presents the neuroimaging features of relatively more common metabolic disorders.

Fetal magnetic resonance imaging in obstetric practice.

Ultrasonography (USG) is the primary imaging method for prenatal diagnosis of fetal abnormalities since its discovery. Although it is the primary method of fetal imaging, it cannot provide sufficient information about the fetus in some conditions such as maternal obesity, oligohydramnios and engagement of the fetal head. At this stage, magnetic resonance imaging (MRI) facilitates examination by providing more specific information. The need and importance of fetal MRI applications further increased by the intrauterine surgery which is currently gaining popularity. Some advantages of fetal MRI over USG are the good texture of contrast, a greater study area and visualization of the lesion and neighbourhood relations, independence of the operators. Also it is not affected by maternal obesity and severe oligohydramnios. However, MRI is inadequate in detecting fetal limb and cardiac abnormalities when compared to USG. MRI is not used routinely in pregnancy. It is used in situations where nonionizing imaging methods are inadequate or ionizing radiation is required in pregnant women. It is not recommended during the first trimester. Contrast agent (Godalinium) is not used during pregnancy. It is believed that MRI is not harmful to the fetus, although the biological risk of MRI application is not known. MRI technique is superior to USG in the detection of corpus callosum dysgenesis, third-trimester evaluation of posterior fossa malformations, bilateral renal agenesis, diaphragmatic hernia and assessment of lung maturation. Especially, it is the method of choice for evaluation of central nervous system (CNS) abnormalities. Fetal MRI has a complementary role with USG. It provides important information for prenatal diagnosis, increases diagnostic accuracy, and in turn affects the prenatal treatment, prenatal interventions and birth plan.

Remote cerebellar hemorrhage after lumbar spinal surgery.

BACKGROUND: Postoperative remote cerebellar hemorrhage (RCH) as a complication of lumbar spinal surgery is an increasingly recognized clinical entity. The aim of this study was to determine the incidence of RCH after lumbar spinal surgery and to describe diagnostic imaging findings of RCH. METHODS: Between October 1996 and March 2007, 2444 patients who had undergone lumbar spinal surgery were included in the study. Thirty-seven of 2444 patients were scanned by CT or MRI due to neurologic symptoms within the first 7 days of postoperative period. The data of all the patients were studied with regard to the following variables: incidence of RCH after lumbar spinal surgery, gender and age, coagulation parameters, history of previous arterial hypertension, and position of lumbar spinal surgery. RESULTS: The retrospective study led to the identification of two patients who had RCH after lumbar spinal surgery. Of 37 patients who had neurologic symptoms, 29 patients were women and 8 patients were men. CT and MRI showed subarachnoid hemorrhage in the folia of bilateral cerebellar hemispheres in both patients with RCH. The incidence of RCH was 0.08% among patients who underwent lumbar spinal surgery. CONCLUSION: RCH is a rare complication of lumbar spinal surgery, self-limiting phenomenon that should not be mistaken for more ominous pathologic findings such as hemorrhagic infarction. This type of bleeding is thought to occur secondary to venous infarction, but the exact pathogenetic mechanism is unknown. CT or MRI allowed immediate diagnosis of this complication and guided conservative management.

Mushroom poisoning in children: liver MDCT findings in three cases.

Wild mushroom poisoning occurs quite frequently in Turkey, usually during late summer and autumn when climatic conditions favour fungal growth. We report the MDCT findings of the liver in three children after mushroom poisoning. In all three patients, precontrast MDCT findings showed diffuse reduction of hepatic attenuation compared with the spleen. Contrast-enhanced MDCT images showed homogeneous contrast enhancement of the liver. All three patients recovered after medical treatment. A follow-up precontrast MDCT examination was performed in one patient in whom the density of the liver parenchyma had returned to normal.